1. Field of the Invention
This invention relates to an automotive device for inhibiting the activation of the starter by means of the ignition switch when the operator is impaired or a theft is being attempted.
2. Prior Art
Devices for testing driver capability and for preventing auto theft are well known.
U.S. Pat. No. 3,886,540 to Sussman et al. discloses a coordination test whereby a plurality of lights and pushbuttons are disposed on a panel. An ignition interlock device prevents vehicle operation unless the operator presses the correct buttons in response to illumination of preselected lights.
U.S. Pat. No. 3,610,943 to Jones discloses a memory test whereby randomly displayed digits must be entered by way of a keyboard after the display is turned off. The correct number must be entered within a fixed interval of time in order to provide a control signal which energizes the starter. A random digit memory test is also disclosed in U.S. Pat. No. 3,942,151 to Takenchi.
U.S. Pat. No. 4,232,289 to Daniel discloses a combination security lock and impaired driver deterrent. A system for testing the reaction of a human subject is disclosed in U.S. Pat. No. 3,794,968 to Hill wherein the magnitude of a quantity which changes at a nonuniform predictable rate utilizing information provided by minimal cues, in particular, a pair of flashing lights which indicate whether the rate of change is being overestimated or underestimated. This analyzer device is interlocked with the ignition system of an automobile.
The flicker fusion frequency phenomenon is utilized in several prior art devices for the testing of vigilance. U.S. Pat. No. 2,495,708 to Draeger et al. discloses an apparatus for performing the flicker fusion test to detect an abnormal condition. The flicker fusion threshold is the greatest number of flashes of light per second which are perceived as a flashing or flickering light. U.S. Pat. Nos. 3,707,710 and 3,761,921 to Adler et al. disclose a device for testing the vigilance of a person based on his flicker fushion threshold, comprising a flicker luminous indicator. In the latter Adler patent, means are provided for adjusting the flicker frequency and for producing an acoustical signal when the frequency falls below a limit value, this acoustical signal indicating that vigilance of the tested person is below an allowable level.
In U.S. Pat. No. 3,665,447 to Bidwell et al., a method and apparatus are disclosed for preventing vehicle operation of an inebriated person using the flicker fusion frequency phenomenon. The light source randomly changes between an illumination which appears flashing to the sober individual and an illumination which appears steady. Means are provided to prevent operation of the vehicle until a signal from the individual and a signal representing the light change are received contemporaneously. The reduction in flicker fusion frequency varies directly with the amount of alcohol ingested. The operational mode of the light (i.e. flickering or steady) is controlled by a timer. The flickering mode is enabled for a predetermined period depending on the length of a notch in the timer, during which period of time the vehicle operator must operate a switch to activate the ignition system.
U.S. Pat. No. 4,093,870 to Epstein discloses an apparatus for testing reflexes based on the activation of a single key or switch after the passage of a certain amount of time, instead of the activation of a correct button or combination of buttons out of a plurality of buttons. The apparatus can be used in conjunction with the ignition of an automobile. The apparatus, after certain lapsed times, creates a condition which is of predetermined time duration. The correct response must be given by the operator within the set time period. If a number of conditions are satisfied, a monostable multivibration outputs a signal of predetermined duration which unlocks the lock. The conditions are satisfied by the entry of a four-digit combination. In response to the display of each digit, the operator must activate a switch before the number is passed in order to operate the lock. The test of reflexes merely requires that the switch be activated within a predetermined time span is response to the display of each digit of the predetermined combination.
The devices disclosed in the Bidwell et al. and Epstein patents suffer from the disadvantage that a display element distinct and separate from those already incorporated in the vehicle dashboard is required. In the case of the Bidwell et al. device, a gas discharge lamp would be a light source suitable for flashing at the flicker fusion frequency. In Epstein, a display cell is connected to the plurality of outputs of decade counter 50 by way of decoder 58, whereby a single-digit number is displayed. Thus, both the Bidwell et al. and Epstein devices for detecting operator impairment suffer from the disadvantage that they cannot be embodied in the form of a modular black box which can be easily plugged into an automotive interface.